Production of artificial filaments, threads and the like



Nov. 12. 1957 J. H. EDWARDS PRODUCTION OF ARTIFICIAL FILAMENTS, THIQEADS AND THE LIKE Filed April 7. 1953 United States Patent PRODUCTIONOF ARTIFICIAL FILAMENTS, I

j THREADS AND THE LIKE John Edwards, Coventry, England, assignor toCourtaulds Limited, London, England, a British company Application April7, 1953, Serial No. 347,360

4 Claims. (Cl.106165) This invention relates to the'production ofartificial filaments, threads, fibres and the like from viscose.

'It is known that viscose filaments produced by the normal spinningprocesses have a crenulated surface and a structure which consists of askin and a core. This skin and core efiect can be demonstrated bystaining the cross-section of the filaments under specific conditionswith selected dyestuffs. In addition to the difference in dyeingaffinity and in swelling property between the skin and core, thecellulose molecules of the skin are believed to be more highlyorientated than those of the core. Processes have been described inUnited States patent specifications Nos. 2,536,014, 2,535,045 and2,535,044 for obtaining modified viscose filaments having anon-crenulated surface and a more diffuse boundary between the skin andcore than unmodified filaments by spinning viscose in the presence ofspecific water-soluble quaternary ammonium compounds, or specificbath-soluble monoamines or specific aliphatic monoamines.

The object of the present invention is to provide a further process forobtaining modified viscose filaments which have substantially no skinand core efiect.

According to the present invention a process for the production ofartificial filaments, threads, fibres and the like comprises extrudingviscose into a coagulating bath containing sulphuric acid and zincsulphate wherein the spinning is carried out in the presence of morethan A of a millimole per 100 grams of viscose of fluorescein. Ifdesired, the fluorescein may be used in the form of its salts, forexample the sodium salt of fluorescein.

In the preferred process according to the invention fluorescein is addedto the viscose but if desired fluorescein may be added to thecoagulating bath or to the viscose and the coagulating bath. Thepreferred minimum concentration for addition to the viscose is 1.5millimoles per 100 grams of viscose and the preferred maximumconcentration is 12 millimoles per 100 grams of viscose. The filamentsobtained exhibit substantially no skin and core effect and in some casesa non-crenulated surface is obtained. The cross-sectional shape and thecrenulation of the surface of the filaments is dependent on the quantityof fluorescein present during spinning. Tests may be necessary in orderto determine the quantity necessary to give a desired cross-sectionalshape and a surface free from crenulations. The coagulating bathpreferably contains from l/z to 15 percent of zinc sulphate.

In addition to the non-crenulated surface and the reduced skin and coreeffect the filaments obtained by the process of the invention have alower water-imbibition than unmodified viscose filaments and they have areduced gel swelling factor.

When spinning according to the process of the present invention thedistance from the jet at which the thread becomes ncutralised isconsiderably increased by the presence of fluorescein in the viscose orthe coagulating bath or both. The process of the present inventionenables unripened or so-called green viscoses to be spun.

/ mixed in for half an hour at centigrade.

This invention is illustrated by the following examples in which thepercentages are by weight.

Example 1 Viscosecontaining 7.8 percent of cellulose, 6.5 percent ofcaustic soda and 2.15 percent of combined sulphur was prepared in theusual manner. When the viscose was 33 hours old from-the beginning ofthe mixing stage and the salt figure was 6.4, 0.5 percent of carbondisulphide on the weight of the viscose was added and was 3 millimolesper grams of viscose of fluorescein in the form of its sodium salt wereadded and the viscose was mixed for a further half an hour. When theviscose was 45 hours old and had a salt figure of 8.9 it was ready forspinning.

The viscose was extruded through a jet having 40 holes, 0.003 inch indiameter into a coagulating bath containing 9.0 percent of sulphuricacid, 20.0 percent of sodium sulphate and 4.0 percent of zinc sulphateto give a thread of denier and 40 filaments. The length of immersion inthe bath was 21 inches and the temperature of the bath was 48centigrade. The thread was drawn from the bath at a rate of 48.6 metresper minute by a godet and then travelled to a second godet rotating at ahigher speed than the first godet, to impart a 20 percent stretch to thethread. The thread was collected in a centrifugal spinning box rotatingat 7,000 R. P. M. The cake obtained was washed free from acid and dried.

The distance from the jet at which the freshly coagulated thread becameneutral was 8 inches whereas an unmodified viscose extruded undersimilar conditions became neutral 2% inches from the jet. The gelswelling factor was 2.7 compared with 3.5 for an unmodified viscose. Thewater imbibition of the finished thread was 87 percent compared with 101percent for a similar thread from an unmodified viscose. Determinationof the axial difiusion coefiicient of a dyestuff along the core of thethread was carried out as described by Hermans in the Textile ResearchJournal, 1948, page 9, using Solophenyl Fast Blue-green BL; nopenetration of dyestufi" was obtained; but for thread from an unmodifiedviscose it was 50 a after impregnation for four hours in 1 percentsolution of the dyestulf at room temperature, indicating that the threadfrom the modified viscose showed no skin and core effect. The thread hada non-crennlated surface and the filaments were dog-bone shape incrosssection.

Example 2 Viscose conatining 7.8 percent cellulose, 6.5 percent causticsoda and 2.15 percent combined sulphur was prepared in the usual mannerand filtered. When the viscose was 33 hours old 0.5 percent of carbondisulphide was added to it and mixed in for 1 hour. The viscose wasdivided into five parts one of which was a blank and to the other fourwere added 1.5, 3.0, 6.0 and 9.0 millimoles per 100 grams of viscose offluorescein in the form of its sodium salt. The viscoses were mixed for15 minutes, evacuated for eight hours and spun through a jet havingforty holes .003 inch in diameter in a bath containing 9.0 percent ofsulphuric acid, 20.0 percent of sodium sulphate and 4.0 percent of zincsulphate at 48 Centigrade. The filaments were drawn off by a godet at 18yards per minute and collected in a Topham box revolving at 4,000 R. P.M. The yarn was subsequently washed and dried.

The salt figures at the time of spinning were 9.5, 9.8, 8.9, 9.3 and 9.3respectively. The cross-sections of the yarns are shown in Figures 1 to5 in which Figure 1 is yarn from unmodified viscose and Figures 2, 3, 4and 5 are yarns from the viscose having 1.5, 3.0, 6.0 and 9.0 millimolesof fluorescein respectively per 100 grams of viscose. These figures showhow the shape and smoothness of outline are affected by the addition offluorescein. The yarn from unmodified viscose has a substantiallycircular cross-section and crenulated surface but the other yarns showelongated cross-sections and smoother outlines with the maximum effectat about 3.0 millimoles of fluorescein per 100 grams of viscose.

What I claim is:

1. Viscose containing more than /4 of a millimole and less than 12millimoles per 100 grams of viscose of a compound selected from thegroup consisting of fluorescein and an alkali metal salt thereof.

2. Viscose containing more than 1.5 and less than 12 millimoles per 100grams of viscose of a compound selected from the group consisting offluorescein and an alkali metal salt thereof.

3. A process for the production of artificial filamentary materialcomprising extruding viscose into an aqueous coagulating bath containingsulphuric acid and zinc sulphate, wherein the viscose contains more thanA of a millimole and less than 12 millimoles per 100 grams of viscose ofa compound selected from the group consisting of fluorescein and analkali metal salt thereof.

4. A process as claimed in claim 3 wherein the viscose contains morethan 1.5 and less than 12 millimoles per 100 grams of viscose of acompound selected from the group consisting of fluorescein and an alkalimetal salt thereof.

References Cited in the file of this patent UNITED STATES PATENTS1,188,777 Hewitt June 27, 1916 1,983,045 Payne Dec. 4, 1934 1,994,709Holzach et al. Mar. 19, 1935 2,136,201 Whitehead Nov. 8, 1938 2,157,544Kline May 9, 1939 2,160,839 Dreyfus June 6, 1939 2,307,760 CreadlickJan. 12, 1943 2,535,044 Cox Dec. 26, 1950 2,535,045 Cox Dec. 26, 19502,536,014 Cox Dec. 26, 1950 2,581,059 Witte Jan. 1, 1952 2,658,888Fischer et a1 Nov. 10, 1953

1. VISCOSE CONTAINING MORE THAN 1/4 OF A MILLIMOLE AND LESS THAN 12MILLIMOLES PER 100 GRAMS OF VISCOSE OF A COMPOUND SELECTED FROM THEGROUP CONSISTING OF FLUORESCEIN AND AN ALKALI METAL SALT THEREOF.